Of same place



UNITED. STATES- OF SAME scnoLz, rL AcE.

PROCESSOF PRODUCING R-ELlEF PLATES FOR PRINTING.

SIEfEGIFIGATION forming part ofLetters PatentNo. 567,

926, dated. September 15, 1896.

Application iiledDeceinber 26,1895. Serial no. 573,390. (in specimens.)

- To all whom it may concern: v I

Be it known that I, O'rrro CAR STRECKER, a subject of the Grand Duke ofHessen, residin g at Mentz, Germany, have invented certain new anduseful Improvements in Processes of Producing Relief-Plates forReprinting Purposes, of which the following is a specification; Myinvention consists of a process for pro ducin g relief-plates, forreprinting purposes, oi. zinc or aluminium-or aluminium coated withanother metal or with an alloy. This process is as follows: Afterthedrawing, reprint, or impression has been applied to a plate of the saidmetal or a picture has been produced photographieally upon it the plateis etched with diluted salt solutions of heavy metals which areelectrically opposite to and hence act on the metal of the said plate,or with mixtures of the said solutions with wit able acids, or withsuitable'aeids alone, until the. color-supports, i. 6., those parts ofthe metal plate which are covered with ink, have attained the requiredheight. In the case of preparing aluminium plates coated with anothermetal or with an alloy the etchingis to be continued till the surface ofthe aluminium is reached or is also corroded. For this etching Iemploy,'preferably, a solution of cupricchlorid or stannous chlorid er amixture of cupric chlorid with very diluted sulfuric acid or only nitricacid, butl do not limit myself to a peculiar concentration or to aparticular salt of metal or to a special acid. After the plate has beenetched with the said solution or the said mixture it' is necessary todissolve or to oxidize those parts of the heavymetals orof heterogeneoussubstances which adhere to the plate mechanically or are combined with.it chemically. This is attained by treating: the plate with acid,preferably, nitric, acid, the concentration of which depends upon thekind of the etch previously employed. Then the dissolved or oxidizedparts are removed by washingthe plate Withwateri .If the plate thustreat d consists whollyof zinc and is designed or bookprintih'g, itneeds no further treatment any more than would an ordinary elcetroplate.If, fhoweveiythe plate consists of coated or uncoated aluminium,thenit'is to bepolis'hed with talcia'nd abrush, in case the binedhydrofluoric acids approximately fixed 1) plate ,isroughened, and thenthe ground, t1 6., the exposed parts of the surface of the plate, Y areto be treated with liqui'dswhich contain phosphoric acids, combinedphosphoric acids, hypophosphorie acid,phosphorous acid, hypophosphorousacid, hydrofluoric acid, com

or the oxyaeids of. sulfur, excepting sulfuric acid. By this treatmentthe exposed aluminium ground is coated with alayer of precipitatedaluminium salt, which is insoluble in water, but which absorbs thelatter and prevents the spreading of the fatty color. The coated or unfcoated aluminium plate is then ready for printing.

. Example 1: Upon an aluminium plate, on which the drawing, reprint, orimpression is protected against etching in the usual manner, a solutionofcupric chlorid in water is poured, which contains one part of crystaLlized cuprie chlorid and five parts of water.

Immediately after having done this the solution is distributed equallyupon and spread unifori'nlyover the plate by means of a bristle 7 5brush. A somewhat violent react-ion takes place on thespot, and underdevelopment of heat, scum and noise copper is separated in the form ofablackish-red layer. Immediately after thereaction has been terminated80. the plate is well rinsed with water. The operation is repeated untilthe color-support (therelief) has attained the desired or rev quirodheight, This height can be previously y employing certain ,85 quantitiesof the solution. In this case for the calculation of the quantity it isto be noticed that one hundred grams'of crystal lized cupric'chloriddissolve about nine grams of aluminium. The height of the relief is goordinarily less than a tenth of a millimeter, which is suificient whenprinting in a 1ithographic press, but it depends always upon the kind ofthe work'in question. After the plate has been washed off it has ablackish- 5 red appearance, originating fromthe copper and from theheterogeneous substances. The plate, however, immediatelybecomes of awhite color upon dissolving these remains (residuum) with strongpurenitric acid. For

this purpose nitric acid of a standardlof twenty-five to forty-five percent. is poured upon the'plate, which is washed 0!? subse-.

quently on the spot. Sometimes it is advisable to protect the fattycolor or ink which isupon the plate against the influence of the nitricacid, before the latter is poured upon the plate, by heating it ormelting it again with colophony, asphaltum, or the like. Then the plateis cleaned and afterward polished absolutely necessary to strengthen thedrawing once more with colophony and then. to melt the latter; Insteadof proceeding in this manner the plate can first be gummed, then, afterthe gum has become dry, washed out with turpentine-oil or the like, andfinally protectedagain and strengthened, as usual.

Example 3: A plate of aluminium coated or lined with another metal, suchas zinc, can

be prepared also in the following manner: The coating of zinc should befreed from all adhering impurities, and then upon or to the surface ofthe coating of zinc the drawing, reprint, or impression is imposed orapplied in the usual manner. Then this drawing, reprint, or impressionis strengthened against the influence of acids, as usual, whereupon theparts of the metallic coating which are not protected by the fatty colorare etched with an acid which does not corrode aluminium, as, forinstance, nitric acid, until the said parts of the coating are removedand the corresponding parts of the aluminium plate are exposed. Thisetching can be performed in one or more times. In the latter casebetween two succeeding etching operations the drawing, reprint, orimpression is to be strengthened again. To best perform this etching, Iusea moderately strong nitric acid. In ordinary cases a diluted etcherof. a standard of five to eight per cent. of nitric acid will answer thepurpose, but I do not limit myself to a fixed dilution. been performedthe plate is washed out, rolled with fresh color, and treated with asolution of phosphoric acids or the like, as before mentioned,.in orderto obtain upon the exposed parts of the aluminium a precipitation ofaluminium salt insoluble in water, but absorbing the latter andpreventing the spreading of the fatty. color.

Example 4:. If the plate consists wholly of zinc, the preparation is thesame as said in the examples 1 and 2, but in this case theexposed partsof the plate need no treatment with a solution ofphosphoricacidsorthelike.

Example 5' When the plate is provided After the etching has with apicture by meansof one of the known photographic processes, then it isto be etched in] the manner previously described, after having itprotected with resin or the like or not, accordingto the employedprocess. Subsequently the plate, when required, is to bethe knownelectromotive series of all bodies.

the heavy metals referred to must be electrically opposite to the metalof the relief-plate.

Having fully described my invention, What I claim as new, and desire tosecure by Letters Patent, is-- g 1. A process of producing relief-platesfor reprinting purposes, of zinc or aluminium or aluminium coated orlined with anothermetal or an" alloy, consisting in etching a plate ofthe said metal, after having imposed thereon a drawing, reprint orimpression or having produced photographically a picture upon it, withsuitable diluted saltsolutions, preferably chlorids, of such heavymetals as are electrically opposite to the metal of the said plate,until the color-supports have attained the required height, and thenremoving the remains adhering to the plate with suitable acids,substantially as described.

2. A process of producing relief-plates for reprinting purposes, of zincor aluminium or aluminium coated or lined with another metal oran alloy,consisting in etching a plate of the said metal, after having imposedthereon a drawing, reprint or impression or having producedphotographically a picture upon it,

:with a mixture of suitable acids and diluted salt solutions, preferablychlorids, of such heavy metals as are electrically opposite to -themetal of the said plate, until the colorsupports have attained therequired height,

and then removing the remains adhering to .the plate with suitableacids, substantially as described.

3. A process of producing relief-plates for reprinting purposes, ofaluminium or aluminium coated or lined with another metal plate, untilthe color-supports have attained the required height, and then removingthe remains adhering to the plate with suitable acids, whereupon theground or exposed parts of the plate after having been polished whenrequired with talc, are treated with-such liquids as will form on theground a precipitate;

of aluminium salt insoluble in water, but absorbing the latter andpreventing the spreading of the fatty color, substantially asdeminiumcoated or lined with another metal or an alloy, consisting in etching aplate of the said metal, after having imposed thereon a,'drawing,reprint or impression or having 4 produced photographically a pictureupon it,

with a mixture of suitable acidsand diluted salt solutions of such heavymetals, as are 7 electrically-oppositeto the metal of the said plate,until the colorsupports have attained the required height, and thenremoving the remains adhering to the plate with suitable acids,whereupon the ground or exposed .parts of the plate, after havingbeenpolishedwhen required with talc, are treated with such liquids as willform on the ground a precipitate of aluminium salt insoluble in water,but absorbing the latter and preventing'the spreading of the fattycolor, substantially as described.

5. A-process of producing relief-plates for reprinting purposes ofaluminium coated or lined with another metal or an alloy, consisting inetching a plate of the said metal, after 5 or impression or havlngproduced photographhaving imposed, thereon a drawing, reprint ic'ally apicture upon it, with an acid, preferably nitric acid, which does notcorrode aluminium, until the non-protected parts of the coating areremoved and the ground or corresponding parts of the aluminium plate areexposed, whereupon the ground is treated with such liquids, which formon the ground a precipitate of aluminium salt insoluble in water, butabsorbing the latter and preventing the spreading of the fatty color,substantially as described. V

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

OTTO CARL STRECKER.

